1. Field of the Invention
This invention relates to invasive medical devices for delivering medications and therapeutic agents into blood vessels, body cavities, organs, tumors and the like. More particularly, the present invention relates to devices for concentrating the delivery of such medications and agents to the walls of the blood vessels and cavities.
2. State of the Art
Various vascular diseases involving vessel walls, for example, arterial sclerosis, aneurysm or other weakening of the vessel wall, occlusive lesions, etc., may benefit from the application of medications to the affected area of the vessel wall. This may be done systemically by injecting medication into the vessel and then allowing the blood to carry the medication to the affected area. The problem with this approach is that high dosages of medication are required to ensure that some small portion reaches the affected area, and the high dosage may be harmful to other organs or body parts. This approach is also expensive and not especially effective. Another approach to treating diseases of vessel walls is to place a block before and after the affected area and then inject medications into that portion of the vessel between the two blocks. The problem with this approach is that blood flow is stopped for a certain amount of time and this, in itself, is dangerous; also, it generally cannot be stopped long enough for effective uptake of the medication by the vessel walls.
Another prior art approach is to thread a catheter through the blood vessel to the affected area and then either supply the medication through the catheter to the affected area or supply the medication through a needle which itself is threaded through the catheter, pierce the vessel wall with the needle, and then supply the medication (see U.S. Pat. No. 5,354,279).
An additional prior art approach to supplying medication to a vessel wall involves the use of an inflatable sleeve positioned adjacent the affected area, where the sleeve includes an annular cavity holding the medication. When the sleeve is inflated to expand outwardly, the medication held in the cavity is placed into contact with the vessel walls and released thereinto. The problem with this approach is that the blood vessel again is blocked for a time and thus a gradual therapeutic regimen is not possible. Other approaches to delivering medication to vessel walls are disclosed in U.S. Pat. Nos. 5,681,281, 5,364,356, and 5,112,305.
It would therefore be desirable to have a device for delivering medication, therapeutic agents, and the like efficiently and effectively to a blood vessel wall, body cavity wall, etc. which is non-occlusive and substantially non-inhibiting of blood flow. It would also be desirable to have such a device which delivers medication substantially directly to a vessel wall, and may do so for an extended period of time.
It is therefore an object of the invention to provide a device for delivering medication, therapeutic agents, and the like efficiently and effectively to a blood vessel wall, body cavity wall, etc.
It is also an object of the invention to provide such a device which is non-occlusive and substantially non-inhibiting of blood flow.
It is another object of the invention to provide such a device which may be easily deployed through the vascular system and other body cavities to desired target locations for delivering the medication, therapeutic agents, and the like.
It is also an object of the invention to provide such a device which is capable of delivering medication substantially directly to a vessel or cavity wall.
It is still another object of the invention to provide such a device, in accordance with one aspect thereof, in which the degree to which blood or other cavity fluid mixes with the medication during administration may be controlled.
The above and other objects are realized in one illustrative embodiment of the invention which includes a resilient tubular wire for threading into a blood vessel or other body passageway to a target wall location which is to be treated with medication or other therapeutic agent. The tubular wire forms a coil at its distal end, and is configured for straightening and threading lengthwise into, through and out the terminal end of a catheter to the target wall location. The wire resumes the coil shape within the blood vessel or body cavity when its distal end exits the terminal end of the catheter. The wire includes a plurality of cuts or openings at least on the outside of the coils for discharging radially outwardly medication carried in the hollow of the wire. Discharge would occur once the coil was in place at the target location by supplying medication through the proximal end of the tubular wire. An occlusive coating formed, for example, by dip coating could be disposed over the wire and openings and then cuts selectively made in the coating to further control discharge of the medication.
In accordance with one aspect of the invention, rather than use a tubular wire, a solid wire could be used, again, having a coil shape at its distal end. A plurality of vesicles would be formed on the outside of the coils for holding fluid or dissolvable solids to be delivered toward the vessel or cavity walls. A sheath or membrane may be disposed over the coil wire to cover the vesicles. Such a membrane may be dissolvable in blood or body cavity fluid to release the contents of the vesicles or the membrane may be made of a permeable material through which the medication could pass.
In accordance with another aspect of the invention, the spacing between adjacent coils may be selectively varied to either increase the mixing of blood or body cavity fluid with the medication (adjacent coils separated some distance), or decrease the mixing (little or no distance between adjacent coils).
In accordance with yet another aspect of the invention, the coiled portion of the tubular wire may be coated with a soft coating of foam, fuzz, or hydrogel to provide a better seal between adjacent wires in the coil and between the coil and the wall of the body passageway. This coating further reduces mixing of the medication and bodily fluids within the passageway.